Sensitive electronic measurements can be disturbed by extraneous electro-magnetic interference. Electro-magnetic interference is generated from a variety of sources including CRTs, electrical equipment and power lines. To minimize the disturbances that these sources of electromagnetic interference introduce to sensitive measurements, electromagnetic shielding must be provided. In medical treatment environments where sensitive measurements like electrocardiographic data acquisition have to be made, a form of electromagnetic shielding must be provided which does not inhibit the medical personnel. The shielding should not hamper or prevent the medical practitioner from being able to perform critical medical functions.
One method to reduce the electromagnetic interference in a medical environment is to provide an entire room that is magnetically shielded with high permeability alloys. This is an effective solution to shielding. However, the disadvantages with this approach are the high cost involved in building a special room and the need to ensconce the patient in it.
Another method of shielding includes coffin-like chambers or cylinders made from similar alloys. These solutions are less costly than shielding an entire room but are undesirable for other reasons. Putting the patient in such a device does not allow for quick access to the patient in emergency situations. This approach can also be uncomfortable to the patient if he or she is claustrophobic or uncomfortable in tight spaces. The situation can be exacerbated if the patient is in pain, injured or critically ill.
High magnetic permeability sheets and associated shielding materials as suggested in U.S. Pat. No. 5,045,637 and U.S. Pat. No. 5,260,128 have been designed for aiding in the manufacturing of magnetically shielded enclosures. The enclosures can be designed to keep electromagnetic radiation in or out. Examples of enclosures include electronic test instrumentation and electromagnetically shielded rooms.
The optimal device for shielding of extraneous electromagnetic signals in the medical environment would shield effectively, be inexpensive, easy to use and be minimally distressing to the patient.